1. Field of the Invention
The present invention relates to a power cable having insulated conductors to present at least one power supply. More particularly, the present invention relates to a cable, which includes a plurality of insulated supply and return conductors, wherein the cross sectional shapes of one or more of the conductors is rectangular, and wherein the power cable may be used in a hybrid cable for supplying power to equipment receiving communications via communication signal carrying mediums, such as optical fibers or conductive elements, e.g., coaxial cables or twisted pairs of conductors.
2. Description of the Related Art
FIG. 1 shows a cell tower 11 having a plurality of remote radio units (RRUs), sometimes referred to as remote radioheads 13, mounted at a top of the tower. A hybrid cable 15 extends from a junction box 17 at a bottom of the tower 11 to the radioheads 13, e.g. 13A, 13B, 13C, . . . , at the top of the tower 11. The hybrid cable 15 provides power and fiber optic pathways and/or electrical signal/control pathways, e.g., via twisted pairs, coaxial cables, from the junction box 17 to the remote radioheads 13, so that the remote radioheads 13 may function to establish a wireless coverage cell in a known manner.
Typically, power is supplied to each remote radiohead 13 by a supply conductor and a return conductor placed separately in the overall jacket of the hybrid cable 15. For example, FIG. 2 shows a cross sectional view of the hybrid cable 15 designed to supply three remote radioheads 13. The hybrid cable 15 includes a jacket 23 surrounding six power conductors, e.g., three power supply conductors 19A, 19B and 19C with red insulation and three power return conductors 21A, 21B and 21C with black or green insulation. The jacket 23 of the hybrid cable 15 may also surround one or more fiber optic cables 25 to send data to, and receive data from, the remote radioheads 13. Typically, the current carrying portions of the power supply and return conductors 19 and 21 are formed of conductive strands, e.g., copper strands, bunched into a circular cross sectional shape and surrounded by an insulation layer having an outer surface with a circular cross sectional shape. FIG. 2 illustrates the inherent air gaps, or interstices 27, formed between abutting power supply and return conductors 19 and 21 due to the outer surfaces with a circular cross sectional shape. Also, FIG. 2 illustrates that optional fillers 29 may be included within the hybrid cable 15 to fill larger void spaces between the one or more fiber optic cables 25 and the power supply and return conductors 19 and 21.
Related art may be found in the following documents, which are herein incorporated by reference: U.S. Pat. Nos. 2,200,776; 3,586,757; 4,219,928; 4,241,498; 4,283,593; 4,787,705; 4,815,814; 4,973,370; 5,804,768; 6,045,374 7,127,144; 7,304,246; 7,346,974; 7,794,132; 8,481,853; and 2003/0108227.